Package sealing machine



N0V- 21, 1957 B. A. ARvlDsoN PACKAGE SEALING MACHINE 2 Sheets-Sheet l Filed May l0, 1965 @i CZ. Zw/M507 -mm L e @QM Nov. 21, 1967 B.'A. ARvlDsoN PACKAGE SALING MACHINE 2 Sheets-Sheet 2 Filed May 1 0, 1965 United States Patent ce 3,353,333 PACKAGE SEALING MACHINE Bengt A. Arvidson, Villa Park, Ill., assignor to Corley- Miller, Inc., a corporation of Ohio Filed May 10, 1965, Ser. No. 454,515 14 Claimst (Cl. S15-379) 'This invention relates to a package sealing machine and, more particularly, to a machine having means providing cont-rolled application of heat to a package wrapped with a heat shrinkable film.

An object of this invention is to provide a new and improved package sealing machine.

Another object of this invention is to provide a new and improved package sealing machine in which a hot plate is positioned on a frame with packages successively moved across the hot plate without direct contact therewith for sealing of a bottom portion of the wrapping material and the package is then conveyed to a shrink tunnel where heat is supplied directly against the lower side of the package and with the entire package being subjected to some heated air to fully shrink the lm around the packaged product.

Another object of the invention is to provide a machine as defined in the preceding paragraph in which external air is supplied to said tunnel, which is heated by heater means associated with the tunnel and wherein the inlet for external air is located above the hot plate to receive air which has been partially heated lby the hot plate and thus increase the eiiiciency of the machine.

Still another object of the invention is to provide a shrink tunnel having side walls with air-emitting nozzles extending along the lower inner side thereof to direct heated air against a package within the tunnel and wherein heater means for the air are located above the nozzles to apply heat to the air immeditely prior to its being emitted from the nozzles and, thus, reduce the over-all wall temperature of the tunnel and this, with the flow of air through the hollow walls of the tunnel, maintains the external wall temperature of the tunnel at a level to prevent burning of personnel working around the machine.

Still another object of the invention is to provide a package sealing machine having a hot plate for sealing the bottom portion of a ilm Wrapped around a package wherein conveying means are provided yfor moving packages across the hot plate, with the conveying means including a pair of endless conveying members located at and travelling along opposite sides of the hot plate, with spaced sections of relatively slippery, heat-resistant and heat-conductiing material releasably secured to the conveying members for carrying packages across the hot plate Without direct contact therebetween and with these sheets being readily replaceable when they become worn r otherwise damaged to thus avoid the replacement of an entire endless belt.

An additional object of the invention is to provide a package sealing machine as defined in the preceding paragraph, wherein a series of bars extend between the conveying members and each of the bars has a leading edge of a sheet releasably secured thereto by a removable spring clip to securely hold the sheet to the conveying members while permitting the simple replacement of a sheet.

Further objects and -advantages will become apparent from the following `detailed description taken in connection with the accompanying drawings in which:

FIG. l is a plan view of the package sealing machine;

FIG. 2 is a side elevation of the machine with parts broken away;

FIG. 3 is an end elevational view with parts broken away, and looking toward the left-hand end of the machine as shown in FIG. 2;

3,353,333 Patented Nov. 21, 1967 FIG. 4 is a fragmentary vertical section on an enlarged scale taken generally along the line 4-4 in FIG. 2; and

FIG. 5 is a fragmentary vertical section taken generally along the line 5 5 in FIG. 4.

While this invention is susceptible of embodiment in many dilierent forms, there is shown in the drawings and will herein be `described in detail an embodiment of the invention with the understanding that the present disclosure is to be considered as an exempliiication of the principles of the invention `and is not intended to limit the invention to the embodiment illustrated. The scope of the invention w-ill be pointed out in the appended claims.

The package sealing machine disclosed herein embodies a frame in the form of a cabinet indicated generally at 10, having supporting legs 11. The frame has two operative stations, with an initial station being provided for sealing iilm wrapped about the bottom of the package and being defined by la hot plate 12. A second station, adjacent the hot plate 12, applies heat about the entire package to shrink the plastic shrink lm forming the package wrapper, with an example of such iilm being polyethylene. This station is defined by ya shrink tunnel 15, upstanding from the cabinet 10.

Means are provided for conveying successive packages across the -hot plate without direct contact between a package and the hot plate and then through the shrink tunnel onto a platform, as indicated at 16. This conveying means comprises a pair of endless conveying members in the form of chains 17 and 18 passing about a pair of spaced drive sprockets 19 on a shaft 19a located adjacent the front of the machine and a pair of spaced guide sprockets 20 adjacent the rear of the machine. The chains 17 and 18 are continuously driven at a desired rate of speed by means of a motor 21 which drives a belt 22 connected to the input of a speed reducer 23, with the output of the speed reducer driving a generally upright belt 24 which is in driving engagement with a pulley 25 secured to the shaft 19a mounting the drive sprockets 19 for the chains 17 and 18.

The conveying members 17 and 18 extend along opposite sides of the lhot plate 12 and have a series of sucessively-spaced conveyor bars 30 extending therebetween at a slight distance above the hot plate 12 whereby there is no contact between a bar and the hot plate. As shown in FIG. 4, a bar 30 has a pair of downwarly descending legs 31 and 32, one at each end thereof, which connect to the endless conveying members.

In order to convey a package, each of the bars 30 has a generally square-shaped piece of material 35 secured thereto and substantially spanning the space between successive bars 30, with a sheet of this material having a package resting on the top thereof, as shown by package P, in FIG. 2. This sheet 35 is formed of a relatively slippery, heat-resistant and heat-conducting material, whereby contact can be made with the hot plate without destruction of the sheet and with relative movement therebetween and transfer of heat from the hot plate to the bottom of the package to seal and slightly shrink the iilm on the underside of the package. An example of such sheet material is fiber glass cloth which has been impregnated with polytetraiiuoroethylene, also known as Teflon. This type of material has very desirable properties -for the application disclosed herein; however, it cannot be easily formed into an endless belt. Such a belt is costly and will not track accurately and, also, when requiring replacement requires entire disassembly of the conveyor structure, which is not required with replacement of the sheets 35, as more fully explained subsequently.

Each of the sheets 35 is secured along its leading edge, only, to its respective conveying bar 30 in the manner shown particularly in FIG. 5. The leading edge of the sheet passes underneath the bar and is wrapped around the top and then an elongate spring clip 36, which is generally U-shaped in cross section, is slipped over the Inaterial to hold it firmly onto the .bar 3). From this it will be seen 'that when a sheet SS'becomes worn or damaged, only the-sheet need be replaced and the replacement can easily be made by 4removing the clip 36 and then putting a new piece of material in place and replacing the clip 36 on the bar 30. The trailing edge of the sheet 35 is not fastened in any way and is free for movement. Thus, the sheet is free to follow the contour of the conveying elements in going down to and along a return length, as shown in FIG. 5. The sheet is supported 'beyond the hot plate 12 by a plate 37, at the same level as the hot plate, and extending through the shrink tunnel 15 and terminating in a curved'end section 38, shown in FIG. 5. This terminal section is curved correspondingly to the sprocket members 20 about which the conveying elements pass. In order to keep the sheets 35 under control on the return length of the conveyor travel, a support plate 39 is positioned within the cabinet to support the sheets, as shown in FIG. 2.

The conveying bars 30 are spaced apart a distance greater than at least one dimension of a package P and thus provide positive package indexing for delivery of packages from the machine. If the packages are being placed on the conveying unit manually, the successive bars 30 provide a general guide for the spacing between packages.

After leaving the hot plate 12, a package P is carried by the conveying means into the shrink tunnel 15. The 'shrink tunnel has entry and exit ends in alignment with the conveyor, with the entry end being shown particularly in FIG. 3 and being effectively closed by partable curtain strips 40. These strips 40 merely hang and readily can be pushed aside by a package as it enters into the shrink tunnel. Reference is made herein to the copending application of Arvidson and Treiber, Ser. No. 426,300, filed J an. 18, 1965, now abandoned, which shows other designs of heat shrink tunnels and nozzles of the type usable herein.

The tunncl'has spaced side walls 50 and 51 extending for the length thereof with a hollow top chamber connecting the h-ollow interiors of the side walls. This top chamber is enclosed and is indicated generally at 52. Each of the side walls 50 and 51A are formed of inner and outer spaced-apart panels, with the wall 50 having panels 53 and 54 and the wall 51 having panels 55 and 56. The spacing of these panels provides for the hollow interiors of the side walls communicating with the top chamber whereby, air can pass therethrough.

Each of Vthe side walls has an air-emitting nozzle at the lower end thereof, with the side wall panel 54 having the nozzle 6@ and the-side wall panel 55 having the nozzle 61. These nozzles can be of the construction shown in the referred to application. The airflow path through the walls of the tunnel to the nozzles 6i) and 61 includes an air inlet to the'top compartment 52, which has a motoroperated blower 65 mounted therein and an adjustable air intake valve 66 mounted at the inlet side of the blower. Air taken in through the valve 66 by the blower is directed into the top compartment S2 and then downwardly through the side walls '50 and 51 for emission through the nozzles 60 and '61, respectively.

Heat is impartedto the air in two ways. First of all, utilization is made of the heat emitted by the hot plate 12 in having the air intake located above the hot plate whereby air enters the intake which is at a temperature substantially above ambient room temperature. The air is then moved downwardly through the side walls for further heating as obtained from the heat within the tunnel itself and, finally, the major part of the heat is normally added to the air by a pair of heaters 70 `and 71 located within the respective side walls immediately above the air outlets 60 and 61. The location of the heaters is important in that the heat is applied to the air immediately prior to emission from the nozzles, so that there is minimum loss of heat. Also, air at a substantially high temperature does not travel through the tunnel from top to bottom and thus the tunnel is sufficiently cool to prevent burning of personnel operating around the equipment. This cooling effect is further enhanced by the fact that air continuously'flows through the tunnel.

As described-in the copending application, previously referred to, the'hot air is emittedfrom the nozzles 60 and 61 at a relatively low level within the tunnel, so-as to be directed against the lower part of the package and with heated air then merely floating up around the package to apply heat to all the film to obtain the desired film shrink effect.

Although not forming part of this invention, suitable electric controls, including thermostats, can be provided to control the operation of the heaters and the motor for the blower. The temperature applied within the tunnel can also be in part controlled by the manual adjustment of the air valve 66, with it being apparent that reduction of the opening will result in less air iiow and,'therefore, more transfer of heat to a certain volume of air to increase the temperature thereof. With this air intake system, there is a constant change of air and it can be maintained at a preset adjustable temperature.

In operation, a package is placed on a conveyor sheet 35 at the front end of the machine and the package then is moved across the hot plate for sealing of the bottom thereof. The package then continues in its movement into the shrink tunnel 15 where hot air is directed against the lower sides of the package. Theheated air causes shrink of the film over the entire surface of the package to form a tight sturdy package and the package is then moved out of the tunnel by the conveying elements onto a platform 16 where it can be picked up or conveyed to a further piece of equipment, such as package weighing and labelling equipment.

I claim:

1. A package sealing machine comprising, a frame having a hot plate for bottom sealing 0f a package, a film shrink tunnel on said frame adjacent said hot plate, means for conveying a package across said hot plate and then through said tunnel, said tunnel having rmeans for directing heated air against the lower part of a package in the tunnel, said means including an external air inlet overlying said hot plate whereby external air supplied is at a temperature above the ambient temperature.

2. A package sealing machine as defined in claim 1 in which vsaid conveying means comprises a plurality of spaced apart bars progressively movable along said frame over said hot plate and through said tunnel, and each bar having ai replaceable sheet of relatively slippery heat resistant material positioned in trailing relation thereto on which a package rests as the package, goes through the machine.

3. A package sealing machine as defined in claim 2 in which a sheet of said material is secured to the associated bar by being wrapped partially therearound, and a removable clip holding the sheet and bar in assembled relation.

4. A package sealing machine as defined in claim 1 in which said tunnel is constructed with side walls having spaced apart panels to define a hollow air ow passage, said air directing means comprising a nozzle in one of said panels opening into said tunnel near the bottom thereof, and heating means for the air positioned between said panels and above and adjacent said nozzle for heating air immediately priorl to exhaust of air through said nozzle into said tunnel.

5. A package sealing machine having a shrink tunnel for shrinking film about a packaged product, said tunnel having entry and exit openings with partable curtains thereacross, side walls for said tunnnel each being of hollow construction and in uid communication with a top chamber, a pair of elongate nozzles associated one with each side wall and opening into the tunnel near the bottom thereof, an air lblower adjacent said top chamber for blowing air through said hollow walls and nozzles, and an air heater in each of said walls immediately above said nozzles.

6. A package sealing machine as dened in claim 5 in which an adjustable air valve is mounted adjacent said air blower for controlling the amount of external air drawn in by the blower and therefore the temperature of air blown through the nozzles.

7. A package sealing machine as defined in claim 6 in which a package bottom sealing hot plate is located in advance of said tunnel and generally underlying said air valve whereby air entering said air valve has been partially heated by said hot plate.

8. A package sealing machine having a hot plate for sealing the lbottom of a package by movement of a package thereacross, a conveying mechanism for packages,

comprising a pair of endless conveyor members travelling along opposite sides of said hot plate, a series of 'bars extending between said members and successively spaced apart a distance gerater than one dimension of a package, and a plurality of sheets of relatively slippery heat-resistant and heat-conducting material secured one to each of said bars along a leading edge thereof to extend therefrom in trailing relation to provide carriers for packages across said hot plate without contact between a package and the hot plate.

9. A package sealing machine as defined in claim 8 in which said bars are connected to said conveyor members to extend at a level spaced above said hot plate.

10. A package sealing machine as defined in claim 8 in which an elongate U-shaped spring clip extends along a bar and holds a sheet leading edge to a bar with said clip lbeing removable from the bar for replacement of a sheet.

11. A package sealing machine as defined in claim 8 in which said sheets are of polytetrauoroethylene impregnated liberglass.

12. A package sealing machine as delined in claim 8 in which a support member is positioned beneath said conveyor members for support of said sheets as the bars progress to the front of the machine along a lower inactive run thereof.

13. A package sealing machine having a shrink tunnel for shrinking iilrn about a packaged product, said tunnel having entry and exit openings, side walls for said tunnel each being of hollow construction and in fluid cornmuniaction with a top chamber, a pair of nozzles associated one with each side wall and opening into the tunnel near the bottom thereof, an air blower for blowing air through said hollow walls and nozzles, and an air heater in each of said walls.

14. A package sealing machine as defined in claim 13 in which a manually adjustable air valve controls the ow of air to the blower and therefore the volume and temperature of air emitted from the nozzles.

References Cited UNITED STATES PATENTS 2,707,018 4/ 1955 Bolton. 3,164,939 1/1965 Burke 53-379 3,309,789 3/196'7 Denker 53-184 X GRANVILLE Y. CUSTER, I R., Primary Examiner. 

1. A PACKAGE SEALING MACHINE COMPRISING, A FRAME HAVING A HOT PLATE FOR BOTTOM SEALING OF SAID PACKAGE, A FILM SHRINK TUNNEL ON SAID FRAME ADJACENT HOT PLATE, MEANS FOR CONVEYING A PACKAGE ACROSS SAID HOT PLATE AND THEN THROUGH SAID TUNNEL, SAID TUNNEL HAVING MEANS FOR DIRECTING HEATED AIR AGAINST THE LOWER PART OF A PACKAGE 